1. Field of the Invention
The present invention relates to a magnetron sputtering device.
2. Description of the Related Art
In recent years, as the size of substrates to be provided with a film thereon has been increased, there has been an increasing demand for larger sputter sources. It is however difficult to increase the size of the target, and therefore one suggested sputter source 103 as shown in FIG. 6 has a plurality of small-size targets 115. The targets 115 of the sputter source 103 are arranged flush with each other, and anode electrodes 113 are provided between the targets 115.
The surfaces of the targets 115 are opposed to a substrate to be provided with a film, and magnetic field forming devices 125 are provided at the rear surface side of the targets 115. While a sputter gas is introduced into a vacuum chamber in which the sputter source 103 is placed, and the anode electrodes 113 are at the ground potential, voltage is applied to the targets 115 at a time. Then, magnetic fields formed by the magnetic field forming devices 125 catch electrons in the vicinity of the target surfaces, and thereby the targets 115 are sputtered.
However, the anode electrodes 113 are placed between the targets 115 in the sputter source 103, and the interval between the targets 115 is increased by the space for the anode electrodes 113. Therefore, the film quality of the part of the substrate opposing the gaps between the targets is different from the film quality of the part opposing the targets.
For example, four targets of ITO (Indium Tin Oxide), each having a length of 1380 mm, a width of 230 mm and a thickness of 6 mm, were provided; and anode electrodes were provided between the targets. Then, DC power of 5.7 kW, 4.6 kW, 4.6 kW, and 5.7 kW were applied the targets, respectively, at a film forming temperature of 200° C. and a film forming pressure of 0.67 Pa, while an argon gas was made to flow at a flow rate of 100 sccm and scanning with a magnetic member was carried out seven times. A thin ITO film having a thickness of an estimated 100 nm was formed on the surface of a substrate having a length of 880 mm, a width of 680 mm, and a thickness of 0.7 mm. It was found as a result of examination of the film that, as shown in FIG. 7, the sheet resistance value was high in positions opposing the gaps between the targets; and the distribution of the sheet resistance value was in the range of 25±100/square. In this way, the quality of the film formed using the conventional sputter source is unequal; and it is difficult to form a thin film of uniform quality on a large-size substrate (see U.S. Pat. Nos. 6,284,106 and 6,093,293).